Characterization of Stirrer Performance in Reverberation Chamber Using Characteristic Modes

In this paper, a new method to compare the effectiveness of a stirrer by calculating the number of characteristic modes of the stirrer is proposed. We find that, for Z-shaped stirrers, the more characteristic modes a stirrer has, the better it works in the reverberation chamber. The number of characteristic modes refer to the number of modes whose characteristic angels fall between 135 and 225 degree. The effectiveness of a stirrer is measured in terms of the field uniformity in the reverberation chamber. The field uniformity is defined as the standard deviation (STD)of the average power of the total electric fields at the eight vertices of the working volume. Three types of stirrers with the same rotational volume are used for verifications.